Use a price tracker. There are many for Amazon, eg https://camelcamelcamel.com/

You can always get your own screen scraper software to do it yourself.

The higher temp is usually for browning, to get a nice golden brown and delicious crust. You need a certain high temperature to achieve carmelization (sugar browning) and Mailliard reaction (protein browning). You can fake this by cooking at a lower temp and then using the broiler. Broilers will burn the food quickly, so watch carefully.

The PCs. The party are the real monsters in any campaign. That old woman hoodwinked is out of 2gp. KILL HER.